A system for coupling steelmaking with a gasification plant, a shaft furnace with a gas base and an electric furnace

Abstract

The utility model discloses a system for gasification device, gas base shaft furnace and electric furnace coupling steelmaking belongs to the steel metallurgy technical field. The utility model provides a system for gasification device, gas base shaft furnace and electric furnace coupling steelmaking, including preprocessing device, conveying device, gasification device, heat transfer device, gas base shaft furnace device, electric furnace device, decarburization device. The system is integrated coal gasification and gas base shaft furnace system, ensures that the synthesis gas (mainly for CO and H2) produced by coal gasification furnace is directly supplied to the shaft furnace, does not need to additionally increase the device and heat, reduces the energy loss of intermediate transmission process. The utility model aims at improving energy utilization efficiency through optimizing system device, reduces production cost to realize the efficient coupling of coal gasification and gas base shaft furnace, electric furnace.

Description

Technical Field

[0001] This utility model relates to the field of iron and steel metallurgy technology, and in particular to a system for steelmaking using a gasification device, a gas-based vertical shaft furnace, and an electric furnace coupled together. Background Technology

[0002] Sponge iron is an excellent iron source and an indispensable impurity diluent for electric arc furnace (EAF) steelmaking, used to produce pure and high-quality steel. It is also the best coolant for converter steelmaking. Global production of sponge iron and hot-pressed sponge iron briquettes has reached nearly 60 million tons per year. Most of the world's sponge iron is produced in gas-based vertical shaft furnaces, with a small amount produced directly in coal-fired rotary kilns. The mainstream technology for global sponge iron production is vertical shaft furnace gas-based reduction, using natural gas as fuel. Coal gasification technology is the process of thermochemically converting coal into syngas, primarily composed of carbon monoxide (CO) and hydrogen (H2), and is one of the core technologies for the clean and efficient utilization of coal. Syngas can be used as a reducing gas for reducing iron ore.

[0003] In existing technologies, such as patent application CN107299175A, which relates to a system and method for coupling fluidized bed gasification, gas-based reduction, and electric arc furnace steelmaking, the fluidized bed gasification technology operates at a pressure of 0.25–0.8 MPa and a bed temperature of 750–900 °C. Limited by the relatively low pressure, the gasification reaction efficiency and the raw material processing capacity of a single fluidized bed are limited, failing to meet the large-scale demand for reducing gas in steel production. Furthermore, constructing multiple fluidized beds would result in high investment costs. Additionally, the relatively low bed temperature of the fluidized bed cannot meet the reducing gas temperature requirements of a gas-based vertical shaft furnace (generally requiring >1000 °C). Therefore, the aforementioned patent application adds a heating furnace to its process flow to heat the syngas generated by the fluidized bed to meet the reducing gas temperature requirements, further increasing energy loss and production costs in the heating process.

[0004] Therefore, there is an urgent need to provide a new technical solution to address the problems of mismatch between syngas and reduced iron production capacity and complex and high-energy-consumption systems in existing technologies, so as to achieve cleaner and more efficient sponge iron production. Utility Model Content

[0005] The purpose of this invention is to provide a system for steelmaking using a gasification device, a gas-based vertical shaft furnace, and an electric furnace, so as to at least partially solve the above-mentioned problems of the prior art.

[0006] To achieve the above objectives, this utility model provides a system for steelmaking using a gasification device, a gas-based vertical shaft furnace, and an electric furnace coupled together, including a pretreatment device (1), a conveying device (2), a gasification device (3), a heat exchange device (4), a gas-based vertical shaft furnace device (5), an electric furnace device (6), and a decarburization device (7).

[0007] The pretreatment device (1) is connected to the conveying device (2) and is used to receive carbon-containing raw materials and pretreat them;

[0008] The conveying device (2) is connected to the pretreatment device (1), the gasification device (3), and the decarbonization device (7) respectively, and is used to convey the product generated after being processed by the pretreatment device (1) to the gasification device (3) and to receive the carbon dioxide generated by the decarbonization device (7).

[0009] The gasification device (3) is connected to the conveying device (2) and the heat exchange device (4) respectively. It receives the product generated after being processed by the pretreatment device (1) from the conveying device (2) and reacts to obtain syngas.

[0010] The heat exchange device (4) is connected to the gasification device (3), the decarbonization device (7), and the gas-based vertical furnace device (5) respectively. It is used to receive the syngas generated by the gasification device (3) and the decarbonized circulating gas output by the decarbonization device (7). The syngas and the decarbonized circulating gas are mixed and heat exchanged through the heat exchange device (4) to obtain mixed gas, which is then output to the gas-based vertical furnace device (5).

[0011] The gas-based vertical shaft furnace device (5) is connected to the heat exchange device (4), the electric furnace device (6), and the decarburization device (7) respectively, and is used to receive the mixed gas generated by the heat exchange device (4). The gas-based vertical shaft furnace device (5) contains iron ore and / or oxide pellets, which react with the mixed gas to obtain sponge iron and circulating gas. The sponge iron is output to the electric furnace device (6), and the circulating gas is output to the decarburization device (7).

[0012] The electric furnace device (6) is connected to the gas-based vertical furnace device (5) for receiving sponge iron. A desulfurizing agent is added to the electric furnace device (6) to reduce and smelt the sponge iron to obtain finished steel and slag.

[0013] The decarbonization device (7) is connected to the conveying device (2), the heat exchange device (4), and the gas-based vertical furnace device (5) respectively. It is used to receive the circulating gas generated by the gas-based vertical furnace device (5) and decarbonize it to obtain carbon dioxide and decarbonized circulating gas.

[0014] In this application, the gas-based vertical shaft furnace is designed with an efficient reduction process in mind, ensuring full contact between the pellets and the reducing gas to improve reduction efficiency. Simultaneously, the airflow distribution within the furnace is optimized to ensure uniform heat distribution and reduce energy consumption.

[0015] Optionally, the carbon-containing raw material includes at least one of coal, biomass, and waste.

[0016] Optionally, the conveying device (2) is at least one of a chain conveyor, a pneumatic conveying system, and a high-pressure pump;

[0017] When the conveying device (2) is a pneumatic conveying system, it is conveyed by receiving carbon dioxide generated by the decarbonization device (7).

[0018] Optionally, in the electric furnace device (6), the desulfurizing agent is a strongly alkaline and / or reducing element;

[0019] The desulfurizing agent includes at least one of lime, fluorite, calcium carbide, calcium silicate desulfurizing agent, and magnesium-based desulfurizing agent.

[0020] Compared with the prior art, the present invention has at least the following advantages:

[0021] (1) System integration advantages: The integrated coal gasification and gas-based vertical shaft furnace system ensures that the syngas (mainly CO and H2) generated by the coal gasification furnace is directly supplied to the vertical shaft furnace without the need for additional heating equipment. By optimizing the process flow, the energy loss in the intermediate transmission process is reduced.

[0022] (2) Advantages of desulfurization: Desulfurizing agent is added to the electric furnace device to complete desulfurization before the production of finished steel, avoiding insufficient desulfurization in the reducing gas stage, which affects the quality of the final finished steel. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a system for coupled steelmaking using a gasification device, a gas-based vertical shaft furnace, and an electric furnace, provided as an embodiment of the present invention.

[0024] Figure label:

[0025] 1. Pretreatment device; 2. Conveying device; 3. Gasification device; 4. Heat exchange device; 5. Gas-based vertical shaft furnace device; 6. Electric furnace device; 7. Decarburization device. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate to understand the embodiments of the utility model described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a product or device comprising a series of units is not necessarily limited to those explicitly listed, but may include other units not explicitly listed or inherent to such product or device.

[0028] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0029] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this utility model according to the specific circumstances.

[0030] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0031] It should be noted that, where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other. The present utility model will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] Example 1

[0033] Embodiment 1 of this utility model provides a system for coupled steelmaking of a gasification device, a gas-based vertical shaft furnace, and an electric furnace. Figure 1 This is a schematic diagram of the system structure. For example... Figure 1As shown, the system comprises: pretreatment device 1, conveying device 2, gasification device 3, heat exchange device 4, gas-based vertical shaft furnace device 5, electric furnace device 6, and decarburization device 7. Among them:

[0034] Pretreatment device 1 pretreatments the received carbon-containing raw materials. Coal powder is obtained by grinding and drying the raw coal, wherein the particle size of the coal powder is 60 μm and the moisture content of the coal powder is 2% wt.

[0035] The conveying device 2 transports the pulverized coal obtained from the coal pretreatment device 1 to the gasification device 3. The conveying device 2 is a pneumatic conveying system that uses CO2 obtained from the decarbonization device 7 to transport the pulverized coal. Initially, the conveying device 2 needs to provide CO2 gas for transporting the pulverized coal. After normal operation, it only needs to use the CO2 provided by the decarbonization device 7 to perform the transport, and no additional gas is required to transport the raw material.

[0036] The gasification unit 3 is connected to the conveying device 2 and the heat exchange device 4. The conveying device 2 receives pulverized coal produced by the coal pretreatment device 1, reacts it to produce syngas, and outputs the syngas to the heat exchange device. The syngas includes hydrogen and carbon monoxide. The operating pressure for syngas production in the gasification unit 3 is 2.0 MPa, and the reaction temperature is 1650℃. The temperature of the syngas is 1450℃. The slag from the reaction in the gasification unit 3 is discharged through a valve at the bottom of the gasification unit. This invention employs a fluidized bed gasification unit with higher operating pressure and greater processing capacity, achieving a better match between the reducing gas production of the gasification unit and the requirements of the gas-based vertical shaft furnace.

[0037] The heat exchanger 4 is also connected to the decarbonization device 7. The decarbonization device 7 receives the furnace top circulating gas generated by the gas-based vertical furnace 5, uses Li4SiO4-based adsorbent particles as the decarbonizing agent to reduce the CO2 content, and obtains decarbonized circulating gas. The heat exchanger 4 mixes the decarbonized circulating gas with the synthesis gas generated by the gasification device 3 to obtain a mixed gas (the initial temperature of the mixed gas before heat exchange is 1200℃). The mixed gas is cooled by exchanging heat with the low-temperature medium in the heat exchanger 4, and the mixed gas at 1080℃ is output to the gas-based vertical furnace 5. The low-temperature medium absorbs heat to generate a high-temperature medium, which can be used to heat other areas or devices. The low-temperature medium is water, which becomes higher-temperature water vapor after absorbing heat.

[0038] The gas-based vertical shaft furnace 5 contains oxidized pellets and receives the cooled mixed gas input from the heat exchange device 4, reacting to produce sponge iron and the furnace top circulating gas. The operating pressure inside the gas-based vertical shaft furnace 5 is 1.7 MPa.

[0039] The gas-based vertical shaft furnace 5 is connected to the electric furnace device 6. The generated sponge iron is transported into the electric furnace device 6, and a desulfurizing agent is added to the electric furnace device 6. The desulfurizing agent is a composite desulfurizing agent of "silicon-calcium + magnesium". Reduction smelting is carried out in the electric furnace device to obtain finished steel and slag. The slag basicity R in the electric furnace device is 2.5, the FeO content is 0.8%, and the temperature is 1650℃.

[0040] By employing the system provided in this embodiment of the invention, the syngas (mainly CO and H2) generated by the coal gasification unit can be directly supplied to the vertical shaft furnace without the need for additional heating equipment. By optimizing the process flow, energy losses during intermediate transmission are reduced, and heat recovery and utilization are achieved through a heat exchange device. This reduces costs, improves efficiency and energy utilization, and enables cleaner and more efficient sponge iron production. Adding a desulfurizing agent to the electric furnace unit ensures desulfurization is completed before producing finished steel, avoiding insufficient desulfurization in the reducing gas stage, which could affect the quality of the final finished steel.

[0041] Example 2

[0042] Embodiment 2 of this utility model provides a system for coupled steelmaking of a gasification device, a gas-based vertical shaft furnace, and an electric furnace. Figure 1 This is a schematic diagram of the system structure. For example... Figure 1 As shown, the system comprises: pretreatment device 1, conveying device 2, gasification device 3, heat exchange device 4, gas-based vertical shaft furnace device 5, electric furnace device 6, and decarburization device 7. Among them:

[0043] Pretreatment device 1 pretreatments the received carbonaceous raw materials. Coal powder is obtained by grinding and drying the raw coal. The coal powder has a particle size of 60 μm and a moisture content of 2% wt. The coal powder and water are then mixed to form a coal slurry. The coal slurry has a particle size of 400 μm and a moisture content of 60%.

[0044] The conveying device 2 transports the coal slurry obtained after processing by the coal pretreatment device 1 to the gasification device 3. The conveying device 2 is a pneumatic conveying system that uses CO2 obtained from the decarbonization device 7 to transport the coal slurry. At this time, the conveying device 2 needs to provide CO2 gas for transporting the coal slurry at the initial moment. After normal operation, it only needs to use the CO2 provided by the decarbonization device 7 to perform the transport, and no additional gas is required to transport the raw material.

[0045] The gasification unit 3 is connected to the conveying device 2 and the heat exchange device 4. The conveying device 2 receives pulverized coal produced by the coal pretreatment device 1, reacts it to produce syngas, and outputs the syngas to the heat exchange device. The syngas includes hydrogen and carbon monoxide. The operating pressure for syngas production in the gasification unit 3 is 8.0 MPa, and the reaction temperature is 1400℃. The temperature of the syngas is 1250℃. The slag from the reaction in the gasification unit 3 is discharged through a valve at the bottom of the gasification unit. This invention employs a fluidized bed gasification unit with higher operating pressure and greater processing capacity, achieving a better match between the reducing gas production of the gasification unit and the requirements of the gas-based vertical shaft furnace.

[0046] The heat exchanger 4 is also connected to the decarbonization device 7. The decarbonization device 7 receives the furnace top circulating gas generated by the gas-based vertical furnace 5, uses N-methyldiethanolamine as a decarbonizing agent to reduce the CO2 content, and obtains decarbonized circulating gas. The heat exchanger 4 mixes the decarbonized circulating gas with the synthesis gas generated by the gasification device 3 to obtain a mixed gas (the initial temperature of the mixed gas before heat exchange is 850°C). The mixed gas is heated by exchanging heat with the high-temperature medium in the heat exchanger 4, and the mixed gas at 920°C is output to the gas-based vertical furnace 5. The high-temperature medium comes from electric heating.

[0047] The gas-based vertical shaft furnace 5 contains iron ore and receives the cooled mixed gas input from the heat exchange device 4, reacting to produce sponge iron and the furnace top circulating gas. The operating pressure inside the gas-based vertical shaft furnace 5 is 7.7 MPa.

[0048] The gas-based vertical shaft furnace 5 is connected to the electric furnace device 6. The sponge iron produced is transported into the electric furnace device 6, and a desulfurizing agent is added to the electric furnace device 6. The desulfurizing agent is a composite desulfurizing agent of "lime + magnesium". Reduction smelting is carried out in the electric furnace device to obtain finished steel and slag. The slag basicity R in the electric furnace device is 3.0, the FeO content is 0.05%, and the temperature is 1700℃.

[0049] By employing the system provided in this embodiment of the invention, a fluidized bed gasification device with higher operating pressure and greater processing capacity is used to achieve a better match between the reducing gas production of the gasification device and the demand of the gas-based vertical shaft furnace. This ensures that the syngas (mainly CO and H2) generated by the coal gasification device is directly supplied to the vertical shaft furnace, and by optimizing the process flow, energy losses during intermediate transmission are reduced. A desulfurizing agent is added to the electric furnace device to complete desulfurization before producing finished steel, avoiding insufficient desulfurization in the reducing gas stage, which would affect the quality of the final finished steel.

[0050] Test case

[0051] A comparison of the gasification device, gas-based vertical shaft furnace, and electric furnace coupled steelmaking system in this utility model with the equipment in patent application CN120272663A yields the following results:

[0052] (1) Advantages of this heat exchange device compared to the three devices in CN 120272663 A:

[0053] The heat exchange device in this invention can control the temperature of the mixed gas through heat exchange. The gas enters the vertical furnace at a suitable temperature range, which helps the reduction of iron pellets (after the mixed gas enters the gas-based vertical furnace, it reacts with the room-temperature iron pellets entering the gas-based vertical furnace. Due to the limitation of reduction efficiency, some of the mixed gas does not react with the iron pellets, but its temperature decreases after heat exchange with the iron pellets. It carries the CO2, water vapor, and ash of the iron pellets after the reaction and is discharged from the top of the vertical furnace. This part of the gas mixes with the high-temperature synthesis gas generated by the gasification device. Depending on the ratio of the two gas volumes, the temperature may be less than 920°C, in the range of 920-1080°C, or greater than 1080°C. The heat exchange device can heat or cool this gas to achieve the effect of controlling the gas temperature).

[0054] Compared with the three devices in CN 120272663 A, it can reduce the overall system investment cost by 14%, reduce energy consumption by 23%, increase productivity by more than 12%, and significantly reduce investment and production costs.

[0055] (2) The advantages of placing the desulfurized material in an electric furnace in this utility model compared to desulfurization in CN 120272663 A:

[0056] This utility model eliminates the need for a pre-installed desulfurization device, reducing investment costs by 8%, simplifying the process system, and improving operational stability.

[0057] This invention performs desulfurization during the steelmaking stage, avoiding the incomplete desulfurization of reducing gas by pre-desulfurization, which does not completely desulfurize iron pellets, and also avoids secondary pollution from desulfurization byproducts.

[0058] (3) The advantages of this decarbonization device in the treatment of circulating gas compared to the decarbonization in CN 120272663A:

[0059] The amount of circulating gas is less than the amount of mixed gas. The decarbonization device is placed in the process of circulating gas treatment, which reduces the amount of gas passing through the decarbonization device and can reduce the energy loss of the decarbonization process.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

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